Communication processing system, communication processing method, base station, and control method and control program thereof

ABSTRACT

This invention provides a communication processing system that stably efficiently uses a resource in a cell managed by a base station. The communication processing system includes a communication terminal, a base station, a plurality of relay stations that relay communication between the communication terminal and the base station, a measurer in the communication terminal that measures strengths of received signals from the plurality of relay stations, and a selector in the base station that selects a relay station that connects the base station and the communication terminal, based on a comparison result of at least one capability of capabilities had by each of the plurality of relay stations, when there exist a plurality of relay stations whose strengths of received signals are more than a threshold.

This application is a National Stage of International Application No.PCT/JP2018/000360, filed on Jan. 10, 2018, which claims the benefit ofpriority from Japanese patent application No. 2017-018830, filed on Feb.3, 2017, the disclosure of which is incorporated herein in its entiretyby reference.

TECHNICAL FIELD

The present invention relates to a communication processing system, acommunication processing method, a base station, and a control methodand a control program thereof.

BACKGROUND ART

Currently, the 3GPP is examining a method of transmitting data from aremote device (remote UE: Remote User Equipment) to a base station via arelay device (relay UE: Relay User Equipment/UE-to-Network Relaydevice), and methods are disclosed in non-patent literatures 1 and 2.

In non-patent literature 1, an architecture model is described in “4.4.3ProSe UE-to-Network Relay for Public Safety”, and a procedure ofestablishing ProSe (D2D) connection via UE-to-Network Relay is describedin FIG. 5.4.4.1-1 in “5.4.4 Direct communication via ProSe UE-to-NetworkRelay”. The explanation of FIG. 5.4.4.1-1 includes an account saying“even after the connection using the relay UE, to reselect a relay UE,the remote UE continuously measures the signal strength of the discoverymessage sent from the relay UE” (see non-patent literature 1, p. 102,lines 14-21).

Additionally, “23.10.4 Sidelink Communication via ProSe UE-to-NetworkRelay” in non-patent literature 2 writes that “whether a UE can operateas a relay UE is controlled by a base station” and that “a remote UEselects a relay UE of the highest PC5 link quality, and if the signalstrength of the PC5 link is less than a preset threshold, a relay UEreselection process is performed” (see non-patent literature 2, p. 283,lines 1-8).

In the above technical field, patent literature 1 discloses a techniqueof selecting a relay station (Relay Node) based on a relay nodeselection rank in a UA (user agent) and notifying an access node of it.In patent literature 1, the relay node selection rank is obtained basedon a relay node power (measured relay node power), a preference orpriority parameter, a power offset parameter, and a history (hysteresisparameter).

CITATION LIST Patent Literature

Patent literature 1: U.S. Patent Application Publication No.2013/0237228

Non-Patent Literature

Non-patent literature 1: 3GPP TS 23.303 V14.1.0 (2016-12)Proximity-based service (ProSe)

Non-patent literature 2: 3GPP TS 36.300 V13.6.0 (2016-12) E-UTRANOverall description

SUMMARY OF THE INVENTION Technical Problem

However, in the techniques described in the above literatures, sinceselection of the relay station is left to the UA, it is impossible tostably efficiently use a resource in a cell managed by the access node(base station).

The present invention enables to provide a technique of solving theabove-described problem.

Solution to Problem

One example aspect of the present invention provides a communicationprocessing system comprising:

a communication terminal;

a base station;

a plurality of relay stations that relay communication between thecommunication terminal and the base station;

a measurer that measures a received signal strength from each of theplurality of relay stations in the communication terminal; and

a selector that selects, in the base station, a relay station thatconnects the base station and the communication terminal, based on acomparison result of at least one capability of capabilities of therelay stations in a case in which there exist a plurality of relaystations whose received signal strengths are more than a threshold.

Another example aspect of the present invention provides a communicationprocessing method of a communication processing system including acommunication terminal, a base station, and a plurality of relaystations that relay communication between the communication terminal andthe base station, comprising:

measuring a received signal strength from each of the plurality of relaystations in the communication terminal; and

selecting, in the base station, a relay station that connects the basestation and the communication terminal, based on a comparison result ofat least one capability of capabilities of the relay stations in a casein which there exist a plurality of relay stations whose received signalstrengths are more than a threshold.

Still other example aspect of the present invention provides a basestation comprising:

a receiver that receives a received signal strength from each of theplurality of relay stations that relay communication between acommunication terminal and the base station, which is measured in thecommunication terminal;

a storage unit that receives a capability from each of the plurality ofrelay stations and stores the capability in association with each relaystation; and

a selector that selects a relay station that connects the base stationand the communication terminal, based on a comparison result of at leastone capability of the capabilities of the relay stations in a case inwhich there exist a plurality of relay stations whose received signalstrengths are more than a threshold.

Still other example aspect of the present invention provides a controlmethod of a base station, comprising:

receiving a received signal strength from each of the plurality of relaystations that relay communication between a communication terminal andthe base station, which is measured in the communication terminal;

receiving a capability from each of the plurality of relay stations andstoring the capability in association with each relay station; and

selecting a relay station that connects the base station and thecommunication terminal, based on a comparison result of at least onecapability of the capabilities of the relay stations in a case in whichthere exist a plurality of relay stations whose received signalstrengths are more than a threshold.

Still other example aspect of the present invention provides a basestation control program for causing a computer to execute a method,comprising:

receiving a received signal strength from each of plurality of relaystations that relay communication between a communication terminal andthe base station, which is measured in the communication terminal;

receiving a capability from each of the plurality of relay stations andstoring the capability in association with each relay station; and

selecting a relay station that connects the base station and thecommunication terminal, based on a comparison result of at least onecapability of the capabilities of the relay stations in a case in whichthere exist a plurality of relay stations whose received signalstrengths are more than a threshold.

Advantageous Effects of Invention

According to the present invention, it is possible to stably efficientlyuse the resource in the cell managed by the base station.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the arrangement of a communicationprocessing system according to the first example embodiment of thepresent invention;

FIG. 2 is a view showing the arrangement of a communication processingsystem according to the second example embodiment of the presentinvention;

FIG. 3A is a block diagram showing the standard arrangement of acommunication processing system according to a technical premise;

FIG. 3B is a sequence chart showing the standard operation of thecommunication processing system according to the technical premise;

FIG. 4 is a sequence chart showing the operation of the communicationprocessing system according to the second example embodiment of thepresent invention;

FIG. 5 is a block diagram showing the functional arrangement of acommunication processing apparatus (base station: eNB) according to thesecond example embodiment of the present invention;

FIG. 6 is a view showing the arrangement of a base station databaseaccording to the second example embodiment of the present invention;

FIG. 7 is a block diagram showing the functional arrangement of acommunication path setter according to the second example embodiment ofthe present invention;

FIG. 8A is a block diagram showing the functional arrangement of a relaystation (relay UE) according to the second example embodiment of thepresent invention;

FIG. 8B is a view showing the arrangement of a relay station databaseaccording to the second example embodiment of the present invention;

FIG. 9 is a block diagram showing the functional arrangement of acommunication terminal (remote UE) according to the second exampleembodiment of the present invention;

FIG. 10 is a block diagram showing the hardware arrangement of thecommunication processing apparatus (base station: eNB) according to thesecond example embodiment of the present invention;

FIG. 11 is a flowchart showing the processing procedure of thecommunication processing apparatus (base station: eNB) according to thesecond example embodiment of the present invention;

FIG. 12 is a view showing the arrangement of a communication processingsystem according to the third example embodiment of the presentinvention;

FIG. 13 is a view showing the arrangement of a base station databaseaccording to the third example embodiment of the present invention;

FIG. 14 is a flowchart showing the processing procedure of acommunication processing apparatus (base station: eNB) according to thethird example embodiment of the present invention;

FIG. 15 is a view showing the arrangement of a communication processingsystem according to the fourth example embodiment of the presentinvention;

FIG. 16 is a view showing the arrangement of a base station databaseaccording to the fourth example embodiment of the present invention;

FIG. 17 is a flowchart showing the processing procedure of acommunication processing apparatus (base station: eNB) according to thefourth example embodiment of the present invention;

FIG. 18 is a view showing the arrangement of a base station databaseaccording to the fifth example embodiment of the present invention; and

FIG. 19 is a flowchart showing the processing procedure of acommunication processing apparatus (base station: eNB) according to thefifth example embodiment of the present invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments of the present invention will now be described indetail with reference to the drawings. It should be noted that therelative arrangement of the components, the numerical expressions andnumerical values set forth in these example embodiments do not limit thescope of the present invention unless it is specifically statedotherwise.

First Example Embodiment

A communication processing system 100 according to the first exampleembodiment of the present invention will be described with reference toFIG. 1. The communication processing system 100 is a system including arelay station.

As shown in FIG. 1, the communication processing system 100 includes acommunication terminal 101, a base station 102, a plurality of relaystations 103, a measurer 111, and a selector 121. The plurality of relaystations 103 relay communication between the communication terminal 101and the base station 102. The measurer 111 in the communication terminal101 measures strengths of signals received from the plurality of relaystations 103. The selector 121 in the base station 102 selects a relaystation that connects the base station 102 and the communicationterminal 101, based on the comparison result of at least one capabilityof the capabilities had by each of the plurality of relay stations, whenthere exist a plurality of relay stations whose strengths of receivedsignal are more than a threshold.

According to this example embodiment, the communication path is selectedin accordance with the at least one capability of the relay station. Itis therefore possible to stably efficiently use the resource in the cellmanaged by the base station.

Second Example Embodiment

A communication processing system according to the second exampleembodiment of the present invention will be described next. In thecommunication processing system according to this example embodiment,the number of connectable communication terminals or the transmissionbandwidth is taken into consideration as the capability information ofeach relay station, and a relay station that relays a communicationterminal and a base station is selected in relay stations for whichreceived signal strengths from the relay stations, which are measured bythe communication terminal, are more than a threshold.

<<Outline of Arrangement of Communication Processing System>>

FIG. 2 is a view showing the arrangement of a communication processingsystem 200 according to this example embodiment. FIG. 2 shows theestablishment of communication paths between a communication terminal210 and a base station 220 via relay stations 231 to 233 in a cellmanaged by the base station 220.

In FIG. 2, B1 to B3 are the measurement results of received signalstrengths from the relay stations 231 to 233 in the communicationterminal 210. In FIG. 2, the strengths of received signals B1 to B3 aremore than a threshold, and the relay stations 231 to 233 are thecandidates of the relay station to be connected.

In the base station 220, a strength of received signal 222 (B1 to B3) iscollected in association with each relay station 221. Additionally, inthe base station 220, the number 223 of connectable communicationterminals and a transmission bandwidth 224 are acquired as thecapability information of each relay station in association with eachrelay station 221. A relay station (Relay-UE2) with the largest number223 of connectable communication terminals or the largest transmissionbandwidth 224 is selected as the relay station that relays the basestation 220 and the communication terminal 210 (see 225). When the relaystation (Relay-UE2) is used, it is possible to suppress the powerconsumption of the communication terminal 210 and also efficiently usethe relay stations 231 to 233. It is therefore possible to stablyefficiently use the resource of the entire communication processingsystem 200.

<<Technical Premise>>

A technical premise concerning the received signal strength measurementwithin the technical scope of this example embodiment will be describedwith reference to FIGS. 3A and 3B.

FIG. 3A is a block diagram showing the standard arrangement of acommunication processing system 300 according to a technical premise.FIG. 3A shows the architecture model of the communication processingsystem 300 shown in FIG. 4.4.3-1 of “4.4.3 ProSe UE-to-Network Relay forPublic Safety” of non-patent literature 1. In addition, FIG. 3B is asequence chart showing the standard operation of the communicationprocessing system 300 according to the technical premise. FIG. 3B showsa procedure of establishing ProSe (D2D) connection via UE-to-NetworkRelay shown in FIG. 5.4.4.1-1 of “5.4.4 Direct communication via ProSeUE-to-Network Relay” of non-patent literature 1.

The outline of the connection establishment procedure (S300) ofUE-to-Network Relay will be described below based on FIG. 5.4.4.1-1. 1.A UE-to-Network Relay node attaches to E-UTRAN to establish PDNconnection. 2. A remote UE searches for a UE-to-Network Relay node usingthe Model-A or Model-B discovery procedure. 3. The remote UE selects theUE-to-Network Relay node and establishes connection. 4. TheUE-to-Network Relay node sets the IP address of the remote UE. 5. TheUE-to-Network Relay node reports the remote UE ID and IP information toMME. 6. The MME reports the user ID and the IP information to S-GW andP-GW. 7. Relay traffic is transmitted/received between the remote UE andthe P-GW.

Note that the explanation of FIG. 5.4.4.1-1 includes an account saying“even after the connection using the relay UE, to reselect a relay UE,the remote UE continuously measures the signal strength of the discoverymessage sent from the relay UE”.

Additionally, “23.10.4 Sidelink Communication via ProSe UE-to-NetworkRelay” in non-patent literature 2 writes that “whether a UE can operateas a relay UE is controlled by a base station” and that “a remote UEselects a relay UE of the highest PC5 link quality, and if the signalstrength of the PC5 link is less than a preset threshold, a relay UEreselection process is performed”.

<<Problem of Technical Premise>>

Here, in step S300 of FIG. 3B, if there occurs necessity of selecting orreselecting a relay UE, the remote UE measures the strengths of receivedsignals of discovery announcement messages sent from a plurality ofrelay

UE candidates, and selects the relay UE candidate of the highest linkquality as the relay UE for itself. However, when the link qualitybetween the remote UE and the relay UE is high, with a few exceptions(interference or reflection or blocking by a building), it is consideredthat the distance between them is also short in many cases. However,since selection of the relay station is left to the measurement of thestrength of received signal by the remote UE, conditions such as thecapability of the relay UE are not taken into consideration, and it isimpossible to stably efficiently use the resource in the cell managed bythe access node (base station). That is, if the remote UE selects arelay UE candidate with the highest received signal strength as therelay UE for itself, selection of a relay UE with an insufficientcapability may occur, although the transmission power of the remote UEis suppressed. As described above, the total resource use in the cellmanaged by the base station is not optimized.

<<Technical Solution According to this Example Embodiment>>

In this example embodiment, to solve or alleviate the above-describedproblem, the base station acquires the strength of received signalmeasured by the remote UE and capability information concerning aplurality of relay UE candidates, and causes the remote UE to select anoptimum relay UE based on the information. Note that the remote UEaccording to this example embodiment includes an IoT (Internet ofThings) device, an MTC (Machine Type Communication) device, an M2M(Machine to Machine) device, and the like.

<<Operation Sequence of Communication Processing System>>

FIG. 4 is a sequence chart showing the operation of the communicationprocessing system 200 according to the second example embodiment of thepresent invention. FIG. 4 shows a sequence of selecting a relay stationbased on a new condition according to this example embodiment in stepS300 of FIG. 3B.

In step S401, the base station 220 sets the frequency of a discoverysignal and the measurement period in the relay stations 231 to 23 n andthe communication terminal 210. After that, the measurement of thestrength of received signal is repeated in synchronism with thefrequency and the measurement period. In addition, in step S403, thebase station 220 acquires the capability information of each of therelay stations 231 to 23 n.

In step S405, each of the relay stations 231 to 23 n transmits adiscovery signal whose signal strength is measured by the communicationterminal 210. Note that in this example embodiment, a case of “Model A”in which a Discovery Announcement Message is periodically transmittedfrom the relay station 430 will be described. However, “Model B” inwhich the communication terminal 410 requests a Discovery ResponseMessage may be used. Then, in step S407, the base station 220 collectsand stores the strength of received signal from the communicationterminal 210 via each relay station, which is measured by thecommunication terminal 210.

In step S409, the base station 220 selects a relay station whosereceived signal strength is more than the threshold as a candidate to beconnected to the communication terminal 210. Furthermore, in step S411,the base station 220 selects a relay station of a higher capability fromthe relay stations selected as candidates in step S409. In step S413,the base station 220 instructs, for the communication terminal 210, therelay station to be connected, thereby establishing the communicationpath.

<<Functional Arrangement of Communication Processing Apparatus>>

FIG. 5 is a block diagram showing the functional arrangement of thecommunication processing apparatus 220 (base station: eNB) according tothis example embodiment. Note that FIG. 5 shows functional componentsassociated with this example embodiment, and other functions provided inthe communication processing apparatus 220 are not illustrated.

The communication processing apparatus 220 includes a communicationcontroller 501, a base station database 502, a relay station capabilityinformation acquirer 503, a communication terminal received signalstrength acquirer 504, a communication path setter 505, a receivedsignal strength measurement parameter setter 506, and a communicationterminal position registrar 507.

The communication controller 501 controls communication between thecommunication processing apparatus 220 and the relay station 230 or ahost device such as an MME. Note that although not illustrated in FIG.5, the communication controller 501 may control communication betweenthe communication processing apparatus 220 and the communicationterminal 210. Additionally, in FIG. 5, one communication controller 501controls communication with both the subordinate device and the hostdevice.

However, a subordinate device communication controller and a host devicecommunication controller may separately be provided.

The base station database 502 stores data necessary for the operation ofthe communication processing apparatus 220 serving as a base station.The relay station capability information acquirer 503 acquires, fromeach relay station, the capability information of the relay station heldby the relay station, and stores it in the base station database 502.The communication terminal received signal strength acquirer 504acquires the strength of received signal from the communication terminalvia each relay station, which is measured by the communication terminal,from the communication terminal via the relay station, and stores it inthe base station database 502. Based on the measurement results of thestrengths of received signals by the communication terminal and thecapability information of each relay station, which are stored in thebase station database 502, the communication path setter 505 instructsto select and set the relay station 230 to be connected to thecommunication terminal 210. The received signal measurement parametersetter 506 refers to the base station database 502, and sets receivedsignal measurement parameters in the communication terminal 210 or therelay station 230. The communication terminal position registrar 507receives the position of the communication terminal 210 located in thecell of the base station, and registers the position in the host devicesuch as an MME.

(Base Station Database)

FIG. 6 is a view showing the arrangement of the base station database502 according to this example embodiment. The base station database 502stores data necessary for the operation of the communication processingapparatus 220 according to this example embodiment.

The base station database 502 includes a parameter storage portion 610that stores parameters used to implement control according to thisexample embodiment for the communication terminal 210 and the relaystation 230 in the cell, a communication terminal information storageportion 620 including the measurement result of the strength of receivedsignal by the communication terminal 210 in the cell controlled by thecommunication processing apparatus 220, and a relay station informationstorage portion 630 including the capability information of the relaystation 230 in the cell controlled by the communication processingapparatus 220.

The parameter storage portion 610 stores a communication terminal signalstrength measurement parameter 611 necessary for discovery processing inthe communication terminal. The communication terminal signal strengthmeasurement parameter 611 includes the frequency of a signal and ameasurement period.

The communication terminal information storage portion 620 stores acommutation terminal position 622, and a signal strength measurementresult 623 from each relay station in association with a communicationterminal ID 621 located in the cell. The signal strength measurementresult 623 stores a relay station ID and a signal strength inassociation with each other.

The relay station information storage portion 630 stores a relay stationposition 632, and relay station capability information 633 inassociation with a relay station ID 631 located in the cell. The relaystation capability information 633 according to this example embodimentincludes the number of communication terminals connectable to each relaystation, the transmission bandwidth of each relay station, and the like.

(Communication Path Setter)

FIG. 7 is a block diagram showing the functional arrangement of thecommunication path setter 505 according to this example embodiment.

The communication path setter 505 includes a communication terminalreceived signal strength acquirer 701, a relay station capabilityinformation acquirer 702, a received signal strength comparer 703, arelay station selector 704, and a selected relay station notifier 705.

The communication terminal received signal strength acquirer 701acquires a strength of received signal from the communication terminalvia a relay station, which is measured by each communication terminaland stored in the base station database 502. The relay stationcapability information acquirer 702 acquires the capability informationof each relay station stored in the base station database 502. Thereceived signal strength comparer 703 compares the strength of receivedsignal by the communication terminal with a threshold, and selects arelay station with a strength of received signal more than the thresholdas a selection candidate. The relay station selector 704 selects a relaystation having a strength of received signal more than the threshold anda higher capability in the comparison results by the received signalstrength comparer 703 as a connection destination for the communicationterminal. The selected relay station notifier 705 notifies thecommunication terminal of the relay station selected by the relaystation selector 704 as the connection destination.

<<Functional Arrangement of Relay Station>>

FIG. 8A is a block diagram showing the functional arrangement of therelay station 230 (relay UE) according to this example embodiment. Notethat FIG. 8A shows functional components associated with this exampleembodiment, and other functions provided in the relay station 230 arenot illustrated.

The relay station 230 includes a communication controller 801, a relaystation database 802, a relay processing parameter acquirer 803, acommunication relay processor 804, a discovery processing controller805, a capability information transmitter 806, and a power supply(battery) 807.

The communication controller 801 controls communication between therelay station 230 and the base station 220 or the communication terminal210. Note that although not illustrated in FIG. 8, the communicationcontroller 801 may control communication with another relay station 230.Additionally, in FIG. 8A, one communication controller 801 controlscommunication with both the base station 220 and the communicationterminal 210. However, a base station communication controller and acommunication terminal communication controller may separately beprovided.

The relay station database 802 stores data necessary for the operationof the relay station 230 according to this example embodiment. The relayprocessing parameter acquirer 803 acquires parameters necessary forrelay processing set from the base station 220, and stores them in therelay station database 802. The communication relay processor 804 relaysthe communication between the base station 220 and the communicationterminal 210 using the relay processing parameters stored in the relaystation database 802. The discovery processing controller 805 controlsdiscovery processing for the connected communication terminal 210 usingparameters stored in the relay station database 802. The capabilityinformation transmitter 806 acquires capabilities of the relay station230 from the relay station database 802 and notifies the base station ofthe capabilities. The power supply (battery) 807 is a power supply usedto operate the relay station 230.

(Relay Station Database)

FIG. 8B is a view showing the arrangement of the relay station database802 according to this example embodiment. The relay station database 802stores data necessary for the operation of the relay station 230according to this example embodiment.

The relay station database 802 includes a parameter storage portion 810that stores parameters used to transmit a signal for signal strengthmeasurement to the communication terminal 210 in the cell, a relaystation information storage portion 820 that stores relay stationinformation including the capability information of the self-relaystation 230, and a communication terminal information storage portion830 including the measurement result of the strength of received signalby the communication terminal 210 in the cell.

The parameter storage portion 810 stores a communication terminal signalstrength measurement parameter 811 necessary for discovery processing inthe communication terminal. The communication terminal signal strengthmeasurement parameter 811 includes the frequency of a signal and ameasurement period.

The relay station information storage portion 820 stores a relay stationposition 822, and relay station capability information 823 inassociation with a relay station ID 821 located in the cell. The relaystation capability information 823 according to this example embodimentincludes the number of communication terminals connectable to each relaystation, the transmission bandwidth of each relay station, and the like.

The communication terminal information storage portion 830 stores acommutation terminal position 832, and a signal strength measurementresult 833 from each communication terminal in association with acommunication terminal ID 831 located in the cell.

<<Functional Arrangement of Communication Terminal>>

FIG. 9 is a block diagram showing the functional arrangement of thecommunication terminal 210 (remote UE) according to this exampleembodiment. Note that FIG. 9 shows functional components associated withthis example embodiment, and other functions provided in thecommunication terminal 210 are not illustrated.

The communication terminal 210 includes a communication controller 901,a communication terminal database 902, a communication processingparameter acquirer 903, a communication processor 904, a received signalstrength measurement processor 905, and a power supply (battery) 906.

The communication controller 901 controls communication between thecommunication terminal 210 and the relay station 230. Note that althoughnot illustrated in FIG. 9, the communication controller 901 may controlcommunication with the base station 220 or another communicationterminal 210.

The communication terminal database 902 stores data necessary for theoperation of the communication terminal 210. The communicationprocessing parameter acquirer 903 acquires parameters necessary forcommunication processing set from the base station 220, and stores themin the communication terminal database 902. The communication processor904 processes communication with the base station 220 via the relaystation 230 using the communication processing parameters stored in thecommunication terminal database 902. Note that the communicationprocessor 904 also performs reselection processing of a relay stationbased on the measurement result of the strength of received signal. Thereceived signal strength measurement processor 905 measures the strengthof received signal transmitted from the relay station 230 using theparameters stored in the communication terminal database 902, andnotifies the base station of the result via the relay station. The powersupply (battery) 906 is the power supply for the communication terminal210.

<<Hardware Arrangement of Communication Processing Apparatus>>

FIG. 10 is a block diagram showing the hardware arrangement of thecommunication processing apparatus 220 (base station: eNB) according tothis example embodiment.

In FIG. 10, a CPU (Central Processing Unit) 1010 is a processor forarithmetic control and executes a program, thereby implementing thefunctional components shown in FIG. 5. The CPU 1010 may include aplurality of processors and execute different programs, modules, tasks,threads, and the like in parallel. A ROM (Read Only Memory) 1020 storesinitial data, the permanent data of programs, and the programs. Anetwork interface 1030 controls communication with the relay station230, the communication terminal 210, or another host device via anetwork.

A RAM (Random Access Memory) 1040 is a random access memory used by theCPU 1010 as a work area for temporary storage. In the RAM 1040, an areato store data necessary for implementation of this example embodiment isallocated. Communication terminal information 1041 is the information ofa communication terminal located in the cell of the communicationprocessing apparatus 220 serving as a base station. The communicationterminal information 1041 includes communication terminal position data,received signal strength data, and the like in association with thecommunication terminal ID of each communication terminal. Relay stationcapability information 1042 is the capability information of a relaystation located in the cell of the communication processing apparatus220 serving as a base station. The relay station capability information1042 includes relay station position data, relay station capabilitydata, and the like in association with the relay station ID of eachrelay station. A received signal measurement parameter 1043 is aparameter used to measure the strength of received signal in and thecommunication terminal 210. A relay station selection table 1044 is atable corresponding to the algorithm of relay station selectionaccording to this example embodiment.

Transmission/reception data 1045 is data transmitted/received to/fromthe relay station 230, the communication terminal 210, or another hostdevice via the network interface 1030.

A storage 1050 stores databases, various kinds of parameters, andfollowing data and programs necessary for implementation of this exampleembodiment. The base station database 502 is the database shown in FIG.6. The storage 1050 stores the following programs. A base stationcontrol program 1051 is a program that controls information processingof the entire communication processing apparatus 220. A communicationterminal received signal strength acquisition module 1052 is a modulethat acquires the strength of received signal measured by thecommunication terminal 210 from the communication terminal via a relaystation, and accumulates the strength of received signal in the basestation database 502. A relay station capability information acquisitionmodule 1053 is a module that acquires capability information held by therelay station 230 from the relay station, and accumulates the capabilityinformation in the base station database 502. A communication pathsetting module 1054 is a module that selects the relay station 230 to beconnected by referring to the strength of received signal serving as acommunication history and the capability information in the base stationdatabase 502, and sets the communication path between the base stationand the communication terminal. A received signal measurement parametersetting module 1055 is a module configured to set parameters used tomeasure the strength of received signal at a predetermined period. Acommunication terminal position registration module 1056 is a moduleconfigured to register the position of a communication terminal locatedin the cell.

Note that programs and data concerning general-purpose functions orother implementable functions of the communication processing apparatus220 are not illustrated in the RAM 1040 and the storage 1050 shown inFIG. 10.

<<Processing Procedure of Communication Processing Apparatus>>

FIG. 11 is a flowchart showing the processing procedure of thecommunication processing apparatus 220 (base station: eNB) according tothis example embodiment. This flowchart is executed by the CPU 1010shown in FIG. 10 using the RAM 1040 and implements the functionalcomponents shown in FIG. 5.

In step S1101, the communication processing apparatus 220 sets thefrequency of the strength measurement signal and the measurement periodin the communication terminal and the relay station. In step S1103, thecommunication processing apparatus 220 acquires, from each relaystation, capability information held by the relay station. In stepS1105, the communication processing apparatus 220 acquires, via eachrelay station, the strength of received signal transmitted from therelay station and measured by the communication terminal.

In step S1107, the communication processing apparatus 220 compares thestrength of received signal by the communication terminal with athreshold, and selects a relay station with a strength of receivedsignal more than the threshold as a candidate. In step S1109, if anotheruncompared relay station remains, the communication processing apparatus220 repeats step S1107.

If another relay station does not remain, in step S1111, thecommunication processing apparatus 220 selects a relay station with thelarger number of connectable communication terminals or transmissionbandwidth from the relay stations selected based on the signalstrengths. In step S1113, the communication processing apparatus 220notifies the communication terminal of the selected relay station, andcauses them to execute data communication processing.

According to this example embodiment, the relay station is selectedbased on the strength of received signal from the communication terminalvia the relay station measured by the communication terminal and thenumber of connectable communication terminals or the transmissionbandwidth that is the capability information of the relay station. It istherefore possible to stably efficiently use the resource in the cellmanaged by the base station.

Third Example Embodiment

A communication processing system according to the third exampleembodiment of the present invention will be described next. Thecommunication processing system according to this example embodiment isdifferent from the second example embodiment in that a relay station isselected using, as the capability information of the relay station, thenumber of currently connected communication terminals or the load amountof the relay station. The rest of the components and operations is thesame as in the second example embodiment. Hence, the same referencenumerals denote the same components and operations, and a detaileddescription thereof will be omitted.

<<Outline of Arrangement of Communication Processing System>>

FIG. 12 is a view showing the arrangement of a communication processingsystem 1200 according to this example embodiment. Note that the samereference numerals as in FIG. 2 denote the same constituent elements inFIG. 12, and a repetitive description thereof will be omitted.

FIG. 12 shows the establishment of a communication path between acommunication terminal 210 and a base station 1220 via relay stations231 to 233 in a cell managed by the base station 1220. In FIG. 12, B1 toB3 are the measurement results of received signal strengths from therelay stations 231 to 233 in the communication terminal 210.

In the base station 1220, a strength of received signal 222 (B1 to B3)is collected in association with each relay station 221. Additionally,in the base station 1220, the number 1223 of connected communicationterminals and a load amount 1224 are acquired as the capabilityinformation of each relay station in association with each relay station221. A relay station (Relay-UE2) with the smallest number 1223 ofconnected communication terminals or the smallest load amount 1224 isselected as the relay station that relays the base station 1220 and thecommunication terminal 210 (see 1225). When the relay station(Relay-UE2) is used, it is possible to suppress the power consumption ofthe communication terminal 210 and also efficiently use the relaystations 231 to 233. It is therefore possible to stably efficiently usethe resource in the overall communication processing system 1200.

(Base Station Database)

FIG. 13 is a view showing the arrangement of a base station database1202 according to this example embodiment. The base station database1202 stores data necessary for the operation of the communicationprocessing apparatus 1220 according to this example embodiment. Notethat the same reference numerals as in FIG. 6 denote the sameconstituent elements in FIG. 13, and a repetitive description thereofwill be omitted.

The base station database 1202 includes a parameter storage portion 610,a communication terminal information storage portion 620, and a relaystation information storage portion 1330 including the capabilityinformation of a relay station 230 in the cell controlled by thecommunication processing apparatus 1220.

The relay station information storage portion 1330 stores a relaystation position 632, and relay station capability information 1333 inassociation with a relay station ID 631 located in the cell. The relaystation capability information 1333 according to this example embodimentincludes the number of communication terminals currently connected toeach relay station, the load amount of each relay station, and the like.

<<Processing Procedure of Communication Processing Apparatus>>

FIG. 14 is a flowchart showing the processing procedure of thecommunication processing apparatus 1220 (base station: eNB) according tothis example embodiment. Note that the same step numbers as in FIG. 11denote the same steps in FIG. 14, and a repetitive description thereofwill be omitted.

When comparison between a threshold and the strength of received signalfrom the communication terminal via each relay station ends, in stepS1411, the communication processing apparatus 1220 selects a relaystation having the smaller number of connected communication terminalsor load amount from the relay stations selected based on the signalstrengths.

According to this example embodiment, the relay station is selectedbased on the strength of received signal from the communication terminalvia the relay station measured by the communication terminal and thenumber of connected communication terminals or the load amount that isthe capability information of the relay station. It is thereforepossible to stably efficiently use the resource in the cell managed bythe base station.

Fourth Example Embodiment

A communication processing system according to the forth exampleembodiment of the present invention will be described next. Thecommunication processing system according to this example embodiment isdifferent from the second example embodiment and the third exampleembodiment in that a relay station is selected using the remainingbattery level of each relay station as the capability information of therelay station. The rest of the components and operations is the same asin the second example embodiment. Hence, the same reference numeralsdenote the same components and operations, and a detailed descriptionthereof will be omitted.

<<Outline of Arrangement of Communication Processing System>>

FIG. 15 is a view showing the arrangement of a communication processingsystem 1500 according to this example embodiment. Note that the samereference numerals as in FIG. 2 denote the same constituent elements inFIG. 15, and a repetitive description thereof will be omitted.

FIG. 15 shows the establishment of a communication path between acommunication terminal 210 and a base station 1520 via relay stations231 to 233 in a cell managed by the base station 1520. In FIG. 15, B1 toB3 are the measurement results of received signal strengths from therelay stations 231 to 233 in the communication terminal 210.

In the base station 1520, a strength of received signal 222 (B1 to B3)is collected in association with each relay station 221. Additionally,in the base station 1520, a remaining battery level 1523 of each relaystation is acquired as the capability information of the relay stationin association with each relay station 221. A relay station (Relay-UE2)with the largest remaining battery level is selected as the relaystation that relays the base station 1520 and the communication terminal210 (see 1525). Note that a relay station whose remaining battery level1523 is less than a predetermined threshold is not selected. When therelay station (Relay-UE2) is used, it is possible to suppress the powerconsumption of the communication terminal 210 and also efficiently usethe relay stations 231 to 233. It is therefore possible to stablyefficiently use the resource of the entire communication processingsystem 1200.

(Base Station Database)

FIG. 16 is a view showing the arrangement of a base station database1502 according to this example embodiment. The base station database1502 stores data necessary for the operation of the communicationprocessing apparatus 1520 according to this example embodiment. Notethat the same reference numerals as in FIG. 6 denote the sameconstituent elements in FIG. 16, and a repetitive description thereofwill be omitted.

The base station database 1502 includes a parameter storage portion 610,a communication terminal information storage portion 620, and a relaystation information storage portion 1630 including the capabilityinformation of a relay station 230 in the cell controlled by thecommunication processing apparatus 1520.

The relay station information storage portion 1630 stores a relaystation position 632, and relay station capability information 1633 inassociation with a relay station ID 631 located in the cell. The relaystation capability information 1633 according to this example embodimentincludes the remaining battery level of each relay station, and thelike.

<<Processing Procedure of Communication Processing Apparatus>>

FIG. 17 is a flowchart showing the processing procedure of thecommunication processing apparatus 1520 (base station: eNB) according tothis example embodiment. Note that the same step numbers as in FIG. 11denote the same steps in FIG. 17, and a repetitive description thereofwill be omitted.

When comparison between a threshold and the strength of received signalfrom the communication terminal via each relay station ends, in stepS1711, the communication processing apparatus 1520 selects a relaystation having a larger remaining battery level of the relay stationfrom the relay stations selected based on the signal strengths.

According to this example embodiment, the relay station is selectedbased on the strength of received signal from the communication terminalvia the relay station measured by the communication terminal and theremaining battery level that is the capability information of the relaystation. It is therefore possible to stably efficiently use the resourcein the cell managed by the base station.

Fifth Example Embodiment

A communication processing system according to the third exampleembodiment of the present invention will be described next. Thecommunication processing system according to this example embodiment isdifferent from the second to fourth example embodiments in that a relaystation is selected by combining various kinds of capability informationof a relay station. The rest of the components and operations is thesame as in the second example embodiment. Hence, the same referencenumerals denote the same components and operations, and a detaileddescription thereof will be omitted.

(Base Station Database)

FIG. 18 is a view showing the arrangement of a base station database1802 according to this example embodiment. The base station database1802 stores data necessary for the operation of a communicationprocessing apparatus 1820 according to this example embodiment. Notethat the same reference numerals as in FIG. 6 denote the sameconstituent elements in FIG. 18, and a repetitive description thereofwill be omitted.

The base station database 1802 includes a parameter storage portion 610,a communication terminal information storage portion 620, and a relaystation information storage portion 1830 including the capabilityinformation of a relay station 230 in the cell controlled by thecommunication processing apparatus 1820.

The relay station information storage portion 1830 stores a relaystation position 632, and relay station capability information 1833 inassociation with a relay station ID 631 located in the cell. The relaystation capability information 1833 according to this example embodimentincludes the number of connectable communication terminals, thetransmission bandwidth, the number of connected communication terminals,the load amount, the remaining battery level of each relay station, andthe like.

Note that as for the relay station capability information 1833, a moreappropriate relay station is selected based on a score obtained byadding a priority order or a weight to each capability information suchthat the resource in the entire cell is efficiently used. It is alsopossible to perform management such that a relay station for which theratio of the number of already connected communication terminals to thenumber of connectable communication terminals is small is selected, or arelay station for which the ratio is equal to or more than a thresholdis not selected. In addition, it is possible to perform management suchthat if the remaining battery level is equal to or less than athreshold, other pieces of capability information are neglected, and therelay station is not selected. Furthermore, the relay station can bemanaged such that the transmission bandwidth or the load amount of therelay station is also associated with another capability or undergoesthreshold determination. The capability information is not limited tothose shown in FIG. 18.

<<Processing Procedure of Communication Processing Apparatus>>

FIG. 19 is a flowchart showing the processing procedure of thecommunication processing apparatus 1820 (base station: eNB) according tothis example embodiment. Note that the same step numbers as in FIG. 11,14, or 17 denote the same steps in FIG. 19, and a repetitive descriptionthereof will be omitted.

When comparison between a threshold and the strength of received signalfrom the communication terminal via each relay station ends, in stepS1911, the communication processing apparatus 1820 selects a relaystation by totally considering the capability information of the relaystations from the relay stations selected based on the signal strengths.Note that step S1911 may include steps S1111, S1411, and S1711 incombination.

According to this example embodiment, the relay station is selected bytotally considering the strength of received signal from thecommunication terminal via the relay station measured by thecommunication terminal and the capability information of the relaystations. It is therefore possible to stably efficiently use theresource in the cell managed by the base station.

Other Example Embodiments

While the invention has been particularly shown and described withreference to example embodiments thereof, the invention is not limitedto these example embodiments. It will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the claims.

The present invention is applicable to a system including a plurality ofdevices or a single apparatus. The present invention is also applicableeven when an information processing program for implementing thefunctions of example embodiments is supplied to the system or apparatusdirectly or from a remote site. Hence, the present invention alsoincorporates the program installed in a computer to implement thefunctions of the present invention by the computer, a medium storing theprogram, and a WWW (World Wide Web) server that causes a user todownload the program. Especially, the present invention incorporates atleast a non-transitory computer readable medium storing a program thatcauses a computer to execute processing steps included in theabove-described example embodiments.

Other Expressions of Example Embodiments

Some or all of the above-described embodiments can also be described asin the following supplementary notes but are not limited to thefollowings.

Supplementary Note 1

There is provided a communication processing system comprising:

a communication terminal;

a base station;

a plurality of relay stations that relay communication between thecommunication terminal and the base station;

a measurer in the communication terminal that measures strengths ofsignals received from the plurality of relay stations; and

a selector in the base station that selects a relay station thatconnects the base station and the communication terminal based on acomparison result of at least one capability of capabilities had by eachof the plurality of relay stations, when there are a plurality of relaystations whose strengths of received signals are more than a threshold.

Supplementary Note 2

There is provided the communication processing system according tosupplementary note 1, wherein the selector comprises a storage unit thatacquires the at least one capability from the each of the plurality ofrelay stations, and stores the at least one capability and the each ofthe plurality of relay stations in association with each other.

Supplementary Note 3

There is provided the communication processing system according tosupplementary note 1 or 2, wherein the at least one capability includesat least one of the number of communication terminals connectable to theeach of the plurality of relay stations and a transmission bandwidth ofthe each of the plurality of relay stations.

Supplementary Note 4

There is provided the communication processing system according to anyone of supplementary notes 1 to 3, wherein the at least one capabilityincludes at least one of the number of communication terminals currentlyconnected to the each of the plurality of relay stations and a loadamount on the each of the plurality of relay stations.

Supplementary Note 5

There is provided the communication processing system according to anyone of supplementary notes 1 to 4, wherein the at least one capabilityincludes a remaining battery level of the each of the plurality of relaystations.

Supplementary Note 6

There is provided the communication processing system according to anyone of supplementary notes 1 to 5, wherein the selector weights the atleast one capability and combines the weighted capabilities, therebyselecting the relay station that connects the base station and thecommunication terminal.

Supplementary Note 7

There is provided the communication processing system according to anyone of supplementary notes 1 to 6, wherein the communication terminalcomprises a Remote UE in 3GPP TS 23.303 V14.1.0, the base stationcomprises an eNB, and the relay station comprises a ProSe UE-to-NWRelay, wherein the measurement of the received signal strength by themeasurer is included in a Discovery Procedure (discovery procedure).

Supplementary Note 8

There is provided the communication processing system according to anyone of supplementary notes 1 to 7, wherein the communication terminalcomprises an IoT device, an MTC device, and an M2M device.

Supplementary Note 9

There is provided a communication processing method of a communicationprocessing system including a communication terminal, a base station,and a plurality of relay stations that relay communication between thecommunication terminal and the base station, comprising:

measuring, in the communication terminal, a received strengths ofsignals received from the plurality of relay stations; and

selecting, in the base station, a relay station that connects the basestation and the communication terminal, based on a comparison result ofat least one capability of capabilities had by each of the plurality ofthe relay stations, when there exist a plurality of relay stations whosestrengths of received signals are more than a threshold.

Supplementary Note 10

There is provided a base station comprising:

a receiver that receives, from a communication terminal, strengths ofsignals which are measured, in the communication terminal, based on thesignals received from a plurality of relay stations that relaycommunication between the communication terminal and the base station;

a storage unit that receives capabilities from each of the plurality ofrelay stations and stores the capabilities and the each of the pluralityof relay stations in association with each other; and

a selector that selects a relay station that connects the base stationand the communication terminal, based on a comparison result of at leastone capability of the capabilities had by the each of the plurality ofrelay stations, when there exist a plurality of relay stations whosestrengths of received signals are more than a threshold.

Supplementary Note 11

There is provided a control method of a base station, comprising:

receiving, from a communication terminal, strengths of signals which aremeasured, in the communication terminal, based on the signals receivedfrom the plurality of relay stations that relay communication between acommunication terminal and the base station;

receiving capabilities from each of the plurality of relay stations andstoring the capability and the each of the plurality of relay stationsin association with each other; and

selecting a relay station that connects the base station and thecommunication terminal, based on a comparison result of at least onecapability of the capabilities had by the each of the plurality of relaystations, when there are a plurality of relay stations whose strengthsof received signal are more than a threshold.

Supplementary Note 12

There is provided a base station control program for causing a computerto execute a method, comprising:

receiving, from a communication terminal, strengths of signals which aremeasured, in the communication terminal, based on the signals receivedfrom the plurality of relay stations that relay communication between acommunication terminal and the base station;

receiving capabilities from each of the plurality of relay stations andstoring the capability and the each of the plurality of relay stationsin association with each other; and

selecting a relay station that connects the base station and thecommunication terminal, based on a comparison result of at least onecapability of the capabilities had by the each of the plurality of relaystations, when there are a plurality of relay stations whose strengthsof received signal are more than a threshold.

The invention claimed is:
 1. A communication processing method of acommunication processing system including a communication terminal, abase station, and a plurality of relay stations relaying communicationbetween the communication terminal and the base station, comprising:measuring, in the communication terminal, strengths of signals receivedfrom the plurality of relay stations; and selecting, in the basestation, a relay station that relays the base station and thecommunication terminal from at least two relay stations included in theplurality of relay stations, based on a comparison result of at leastone capability of capabilities of each of the at least two relaystations, when strengths of signals received from the at least two relaystations by the communication terminal are greater than a threshold. 2.The communication processing method according to claim 1, furthercomprising: acquiring the capabilities from the each of the plurality ofrelay stations; and storing the capabilities and the each of theplurality of relay stations in association with each other.
 3. A basestation comprising: a receiver that receives, from a communicationterminal, strengths of signals which are measured, in the communicationterminal, based on the signals received from a plurality of relaystations relaying communication between the communication terminal andthe base station; a storage unit that receives capabilities from each ofthe plurality of relay stations and stores the capabilities and the eachof the plurality of relay stations in association with each other; and aselector that selects a relay station that relays the base station andthe communication terminal from at least two relay stations included inthe plurality of relay stations, based on a comparison result of atleast one capability of the capabilities of the each of the at least tworelay stations, when strengths of signals received from the at least tworelay stations by the communication terminal are greater than athreshold.
 4. The base station according to claim 3, wherein the atleast one capability includes a number of communication terminalsconnectable to the each of the at least two relay stations and atransmission bandwidth of the each of the at least two relay stations.5. The base station according to claim 4, wherein the at least onecapability further includes the number of communication terminalscurrently connected to the each of the at least two relay stations and aload amount on the each of the at least two relay stations.
 6. The basestation according to claim 4, wherein the at least one capabilityincludes a remaining battery level of the each of the at least two relaystations.
 7. The base station according to claim 5, wherein the at leastone capability includes a remaining battery level of the each of the atleast two relay stations.
 8. The base station according to claim 5,wherein the selector weights the at least one capability and combinesthe weighted capabilities, thereby selecting the relay station thatrelays the base station and the communication terminal.
 9. The basestation according to claim 7, wherein the selector weights the at leastone capability and combines the weighted capabilities, thereby selectingthe relay station that relays the base station and the communicationterminal.
 10. The base station according to claim 3, wherein the atleast one capability includes a number of communication terminalscurrently connected to the each of the at least two relay stations and aload amount on the each of the at least two relay stations.
 11. The basestation according to claim 10, wherein the at least one capabilityincludes a remaining battery level of the each of the at least two relaystations.
 12. The base station according to claim 3, wherein the atleast one capability includes a remaining battery level of the each ofthe at least two relay stations.
 13. The base station according to claim3, wherein the selector weights the at least one capability and combinesthe weighted capabilities, thereby selecting the relay station thatrelays the base station and the communication terminal.
 14. The basestation according to claim 3, wherein the communication terminalcomprises a Remote UE (User Equipment) in 3GPP (3rd GenerationPartnership Project) 23.303 V14.1.0, the base station comprises an eNB(evolved Node B), and the relay station comprises a ProSe(Proximity-based service) UE-to-NW (Network) Relay, wherein themeasurement of the received signal strength by the measurer is includedin a Discovery Procedure.
 15. The base station according to claim 3,wherein the communication terminal comprises an IoT (Internet of Things)device, an MTC (Machine Type Communication) device, and an M2M (Machineto Machine) device.
 16. The base station according to claim 3, whereinthe at least one capability includes a number of communication terminalsconnectable to the each of the at least two relay stations.
 17. The basestation according to claim 3, wherein the at least one capabilityincludes a transmission bandwidth of the each of the at least two relaystations.
 18. The base station according to claim 3, wherein the atleast one capability includes a number of communication terminalscurrently connected to the each of the at least two relay stations. 19.The base station according to claim 3, wherein the at least onecapability includes a load amount on the each of the at least two relaystations.
 20. A non-transitory computer-readable storage medium storinga base station control program for causing a computer to execute amethod, comprising: receiving, from a communication terminal, strengthsof signals which are measured, in the communication terminal, based onthe signals received from the plurality of relay stations relayingcommunication between a communication terminal and the base station;receiving capabilities from each of the plurality of relay stations andstoring the capabilities and the each of the plurality of relay stationsin association with each other; and selecting a relay station thatrelays the base station and the communication terminal from at least tworelay stations, based on a comparison result of at least one capabilityof the capabilities had by the each of the at least two relay stations,when strengths of signals received from the at least two relay stationsby the communication terminal are greater than a threshold.